While studies have associated several gene variants with cholesterol levels, exactly how those variants impact the risk of cardiovascular disease is unclear.

Since the effects of these individual gene variants appear slight, the research team looked at a combination of nine SNPs previously associated with cholesterol levels. They analyzed data from 5,414 Swedish adults who participated in a major prospective epidemiological study and correlated data including standard measurements of HDL and LDL cholesterol and the presence of the nine gene variants with information on the participants’ subsequent medical history.

After the initial genotyping of participants not receiving lipid-lowering therapy, participants were assigned a genotype score ranging from 0 to 18 based on how many copies of the unfavorable SNPs they carried. The scientists found that higher genotype scores did reflect higher LDL and lower HDL levels. Importantly, those with genotype scores of 11 or higher had a 63% greater risk of a cardiovascular event than those with scores of ninen or lower.

Testing using the panel of nine SNPs was not better than using standard risk factors for predicting cardiac events in the overall population. Among participants classified at intermediate risk by standard measures, however, adding the nine-SNP panel significantly improved the ability to distinguish elevated or reduced risk levels, according to the researchers.

The study was performed by investigators at Massachusetts General Hospital, Harvard Medical School, Children's Hospital Boston, the Broad Institute, University Hospital Malmö, Lund University, Chalmers University of Technology, and Helsinki University. The paper appears in the New England Journal of Medicine.